Alba Strain Research Articles

Rhizospheric-Derived Nocardiopsis alba BH35 as an Effective Biocontrol Agent Actinobacterium with Antifungal and Plant Growth-Promoting Effects: In Vitro Studies.

The biocontrol approach using beneficial microorganisms to control crop diseases is becoming an essential alternative to chemical fungicides. Therefore, new and efficient biocontrol agents (BCA) are needed. In this study, a rhizospheric actinomycete isolate showed unique and promising antagonistic activity against three of the most common phytopathogenic fungi, Fusarium oxysporum MH105, Rhizoctonia solani To18, and Alternaria brassicicola CBS107. Identification of the antagonistic strain, which was performed according to spore morphology and cell wall chemotype, suggested that it belongs to the Nocardiopsaceae. Furthermore, cultural, physiological, and biochemical characteristics, together with phylogenetic analysis of the 16S rRNA gene (OP869859.1), indicated the identity of this strain to Nocardiopsis alba. The cell-free filtrate (CFF) of the strain was evaluated for its antifungal potency, and the resultant inhibition zone diameters ranged from 17.0 ± 0.92 to 19.5 ± 0.28 mm for the tested fungal species. Additionally, the CFF was evaluated in vitro to control Fusarium wilt disease in Vicia faba using the spraying method under greenhouse conditions, and the results showed marked differences in virulence between the control and treatment plants, indicating the biocontrol efficacy of this actinomycete. A promising plant-growth promoting (PGP) ability in seed germination and seedling growth of V. faba was also recorded in vitro for the CFF, which displayed PGP traits of phosphate solubilization (48 mg/100 ml) as well as production of indole acetic acid (34 μg/ml) and ammonia (20 μg/ml). This study provided scientific validation that the new rhizobacterium Nocardiopsis alba strain BH35 could be further utilized in bioformulation and possesses biocontrol and plant growth-promoting capabilities.

Taxonomic and Bioactivity Characterizations of Mameliella alba Strain LZ-28 Isolated from Highly Toxic Marine Dinoflagellate Alexandrium catenella LZT09.

Microalgae host varied microbial consortium harboring cross-kingdom interactions with fundamental ecological significance in aquatic ecosystems. Revealing the complex biofunctions of the cultivable bacteria of phycosphere microbiota is one vital basis for deeply understanding the mechanisms governing these dynamic associations. In this study, a new light-yellow pigmented bacterial strain LZ-28 was isolated from the highly-toxic and harmful algal bloom-forming dinoflagellate Alexandrium catenella LZT09. Collective phenotypic and genotypic profiles were obtained to confidently identify this strain as a new Mameliella alba member. Comparative genomic analysis showed that strain LZ-28 shared highly similar functional features with other four marine algae-derived M. alba strains in spite of their distinctive isolation sources. Based on the bioactivity assaying, the mutual growth-promoting effects between bacterial strain LZ-28 and algal strain LZT09 were observed. After the culture conditions were optimized, strain LZ-28 demonstrated an extraordinary production ability for its bioflocculanting exopolysaccharides (EPS). Moreover, the portions of two monosaccharides glucose and fucose of the EPS were found to positively contribute to the bioflocculanting capacity. Therefore, the present study sheds light on the similar genomic features among the selected M. alba strains, and it also reveals the potential pharmaceutical, environmental and biotechnological implications of active EPS produced by this new Mameliella alba strain LZ-28 recovered from toxic bloom-forming marine dinoflagellate.

Two steps purification, biochemical characterization, thermodynamics and structure elucidation of thermostable alkaline serine protease from Nocardiopsis alba strain OM-5

The Nocardiopsis alba strain OM-5 showed maximum protease production in submerged culture. The OM-5 protease was purified by hydrophobic interaction chromatography. The purified protease of 68 kDa showed maximum activity (3312 ± 1.64 U/mL) at 70 °C and was quite stable at 80 °C up to 4 M NaCl (w/v) at pH 9. The purified protease showed significant activity and stability in different cations, denaturing agents, metal ions, and osmolytes. The thermodynamic parameters including deactivation rate constant (Kd) and half lives (t1/2) at 50–80 °C were in the range of 2.50 × 10−3 to 5.50 × 10−3 and 277.25–111.25 min respectively at 0–4 M NaCl. The structural stability of the OM-5 protease under various harsh conditions was elucidated by circular dichroism (CD) spectroscopy followed by K2D3 analysis revealed that the native structure of OM-5 protease was stable even in sodium dodecyl sulfate and Tween 20 indicated by increased α-helices content assisted with decreased β-sheets content.

Complete Genome Sequence of Mameliella alba Strain KU6B, a Cyclohexylamine-Utilizing Marine Bacterium.

Here, we report the complete genome sequence of Mameliella alba strain KU6B, a bacterium newly isolated from seawater of Boso Peninsula in Japan that is capable of utilizing cyclohexylamine. The complete genome contained a 5,386,988-bp circular chromosome and three circular plasmids of 256,516, 112,434, and 76,727 bp.

Transcriptomic analysis of two endophytes involved in enhancing salt stress ability of Arabidopsis thaliana

Soil salinity is one of the serious environmental issues worldwide. In the present study, we made an attempt to isolate endophytic actinobacteria from halophyte and evaluate their growth promoting ability in Arabidopsis thaliana under salt stress through transcriptomic analysis. Two endophytic strains SYSU 333322 and SYSU 333140 were isolated and 16S rRNA gene sequence analysis suggests that these strains belong to Arthrobacter endophyticus and Nocardiopsis alba, respectively. To evaluate the growth promoting ability of two strains in Arabidopsis thaliana four experimental set up were designed. Set up designated s322 and s140 includes strains SYSU 333322 and SYSU 333140, respectively inoculated with A. thaliana under salt stress; set up designated MS322 and MS140 includes strains SYSU 333322 and SYSU 333140, respectively inoculated with A. thaliana without salt stress; MS includes seedlings without bacterial strains and salt stress; C150 includes seedlings grown in 150 mmol L−1NaCl. A. endophyticus strain SYSU 333322 and N. alba strain SYSU 333140 were efficient to promote A. thaliana growth under salt stress A. endophyticus strain SYSU 333322 was more efficient than N. alba strain SYSU 333140 for growth promotion. Although A. endophyticus strain SYSU 333322 and N. alba strain SYSU 333140 were isolated from the same host, their mechanism of growth promotion in A. thaliana under salt stress was different. Gene encoding for chlorophyll a reductase, peptide-methionine (R)-S-oxide reductase, and potassium ion uptake were up-regulated when A. thaliana inoculated with strain SYSU 333322 and SYSU 333140 under salt stress. Pathways such as carotenoid biosynthesis, phenylalanine metabolism, phenylpropanoid biosynthesis, glycerolipid metabolism, and nitrogen metabolism played a crucial role in enhancing the salt stress tolerance of A. thaliana. Our results suggest that different bacteria have a different mechanism to promote plant growth under salt stress and hence it is necessary to understand the mechanism to overcome soil salinity problem.

Gene structure and comparative study of two different plastic-degrading esterases from Roseateles depolymerans strain TB-87

The structures of two genes from Roseateles depolymerans strain TB-87 encoding the esterases Est-H and Est-L, which can degrade aliphatic-aromatic copolyesters, were annotated. Two open reading frames (ORFs) consisting of 1083 bp and 870 bp nucleotides, corresponding to est-H and est-L, encoding enzymes of 290 and 289 amino acids, respectively, were predicted. In addition, another ORF consisting of 735 bp encoding a chaperone-like protein (Est-Ch) of 244 amino acids was identified in the intergenic region of est-H and est-L. The presence of a promoter region upstream of est-H and the absence of a terminator region downstream of the ORF and vice versa for est-Ch, suggests that est-H and est-Ch are polycistronically expressed. A homology search for Est-H and Est-L revealed homology with plastic degrading enzymes, such as esterases and cutinases, while Est-Ch showed homology with a bacterial lipase chaperone. As consensus lipase sequences (-Gly-His-Ser-Met-Gly-) were observed in these enzymes, Est-H and Est-L were hypothesized to be hydrolases with serine (Ser) in their active center. Three-dimensional structures of Est-H and Est-L without their putative signal sequences were constructed using Est119 from Thermobifida alba strain AHK119 as the template; the structures and positions of the catalytic triad (Ser, Asp, His) active centers were similar to those of Est119. A mutant strain in which the annotated esterase-encoding genes were disrupted using a homologous recombination method lost the ability to form a clear zone on poly(butylene succinate-co-adipate (PBSA) emulsion-overlaid nutrient agar plates. Characterization of the esterases from strain TB-87 could contribute to the development of novel biodegradable plastics with unique properties such as recyclable monomers.

Beggiatoa leptomitoformis sp. nov., the first freshwater member of the genus capable of chemolithoautotrophic growth.

A strain of filamentous sulfur bacteria was isolated from freshwater spring contaminated with residential and agricultural wastewater in Moscow region, Russia. According to the results of phylogenetic analysis, strain D-402T belonged to the genus Beggiatoa within the family Beggiatoaceae of the class Gammaproteobacteria. Within the genus Beggiatoa, strain D-402T was most closely related to Beggiatoa alba strains. Strain D-402T had a DNA G+C content 42.1 mol%. The DNA-DNA hybridization value between strain D-402T and Beggiatoa alba strain B15LD was 33 %. Predominant fatty acids were C18 : 1 (46.1 and 53.3 %), C16 : 0 (15.5 and 16.2 %) and C16 : 1 (32.9 and 25.4 %) for strains D-402T and B15LD, respectively. In contrast to known representatives of Beggiatoa, strain D-402T was capable of chemolithoautotrophic growth with sulfide and thiosulfate as electron donors. Oxidation of sulfide and thiosulfate was accompanied by deposition of sulfur globules within the cells. Strain D-402T was capable of heterotrophic growth. The strain was capable of using different organic compounds, sulfur compounds and hydrogen as electron donors. Based on these observations, strain D-402T is considered as a representative of a species Beggiatoa leptomitoformis sp. nov. of the genus Beggiatoa. The type strain is D-402T (=DSM 14946T=UNIQEM U 779T).

Whole-Genome Sequence of Nocardiopsis alba Strain ATCC BAA-2165, Associated with Honeybees

The actinomycete Nocardiopsis alba was reportedly associated with honeybees in separate occurrences. We report the complete genome of Nocardiopsis alba ATCC BAA-2165 isolated from honeybee guts. It will provide insights into the metabolism and genetic regulatory networks of this genus of bacteria that enable them to live in a range of environments.

Purification strategies, characteristics and thermodynamic analysis of a highly thermostable alkaline protease from a salt-tolerant alkaliphilic actinomycete, Nocardiopsis alba OK-5

An alkaline protease from salt tolerant alkaliphilic actinomycetes, Nocardiopsis alba strain OK-5 was purified to homogeneity by 27 and 13 fold with a yield of 35 and 13% using two-steps and one-step method, respectively. The purification methods involved hydrophobic interaction on phenyl sapharose matrix. The apparent molecular mass was 20kDa. The temperature optimum shifted from 70 to 80°C in 4M NaCl and 30% Na-glutamate, with significant stability at 60–80°C in Na-glutamate. Deactivation rate constant (Kd) increased and half life (t1/2) decreased with the increasing temperatures from 37 to 80°C. The order of stability was: 30% Na-glutamate>4M NaCl>2M NaCl>0M NaCl. The enzyme was stable even at 80°C in 30% Na-glutamate with Kd 4.11 and t1/2 168.64min. The activation energies (E), enthalpy (ΔH*) and entropy (ΔS*) for protease deactivation in with Na-glutamate were 31.97kJ/mole, 29.23kJ/mole and −211.83J/mole, respectively. The change in free energy (ΔG*) for protease deactivation at 60°C in 30% Na-glutamate was 101.70kJ/mole. Protease had the highest activity and stability at pH 10–11. While the enzyme was highly resistant against chemical denaturation, it had varied responses to metal ions. Complete inhibition by PMSF confirmed serine nature of the protease. Na-glutamate, H2O2, β-mercaptoethanol and different surfactants enhanced the activity.

ChemInform Abstract: Topostatin, a Novel Inhibitor of Topoisomerases I and II Produced by Thermomonospora alba Strain No. 1520. Part 1. Taxonomy, Fermentation, Isolation and Biological Activities.

ChemInform Abstract: Topostatin, a Novel Inhibitor of Topoisomerases I and II Produced by Thermomonospora alba Strain No. 1520. Part 1. Taxonomy, Fermentation, Isolation and Biological Activities.

Diversity of polyester-degrading bacteria in compost and molecular analysis of a thermoactive esterase from Thermobifida alba AHK119

More than 100 bacterial strains were isolated from composted polyester films and categorized into two groups, Actinomycetes (four genera) and Bacillus (three genera). Of these isolates, Thermobifida alba strain AHK119 (AB298783) was shown to possess the ability to significantly degrade aliphatic-aromatic copolyester film as well as decreasing the polymer particle sizes when grown at 50 degrees C on LB medium supplemented with polymer particles, yielding terephthalic acid. The esterase gene (est119, 903 bp, encoding a signal peptide and a mature protein of 34 and 266 amino acids, respectively) was cloned from AHK119. The Est119 sequence contains a conserved lipase box (-G-X-S-X-G-) and a catalytic triad (Ser129, His207, and Asp175). Furthermore, Tyr59 and Met130 likely form an oxyanion hole. The recombinant enzyme was purified from cell-free extracts of Escherichia coli Rosetta-gami B (DE3) harboring pQE80L-est119. The enzyme is a monomeric protein of ca. 30 kDa, which is active from 20 degrees C to 75 degrees C (with an optimal range of 45 to 55 degrees C) and in a pH range of 5.5 to 7.0 (with an optimal pH of 6.0). Its preferred substrate among the p-nitrophenyl acyl esters (C2 to C8) is p-nitrophenyl hexanoate (C6), indicating that the enzyme is an esterase rather than a lipase.

A mycorrhiza helper bacterium enhances ectomycorrhizal and endomycorrhizal symbiosis of Australian Acacia species.

The aims of this study were to test the effects of a mycorrhiza helper bacterium (MHB), Pseudomonas monteilii strain HR13 on the mycorrhization of (1) an Australian Acacia, A. holosericea, by several ectomycorrhizal fungi or one endomycorrhizal fungus Glomus intraradices, and (2) several Australian Acacia species by Pisolithus alba strain IR100 under glasshouse conditions. Bacterial inoculant HR13 significantly promoted ectomycorrhizal colonization for all the Acacia species, from 45.8% ( A. mangium) to 70.3% ( A. auriculiformis). A stimulating effect of HR13 on the ectomycorrhizal establishment was recorded with all the fungal isolates (strains of Pisolithus and Scleroderma). The same effect of bacteria on the frequency of endomycorrhizal colonization of A. holosericea seedlings by G. intraradices with vesicles and hyphae frequencies was recorded. The stimulation of saprophytic fungal growth by MHB is usually the main mechanism that could explain this bacterial effect on mycorrhizal establishment. MHB could stimulate the production of phenolic compounds such as hypaphorine and increase the aggressiveness of the fungal symbiont. However, no significant effect of MHB on fungal growth was recorded with Scleroderma isolates under axenic conditions but positive bacterial effects were observed with Pisolithus strains. From a practical viewpoint, it appears that MHB could stimulate the mycorrhizal colonization of Australian Acacia species with ectomycorrhizal or endomycorrhizal fungi, and could also facilitate controlled mycorrhization in nursery practices where Acacia species are grown for forestation purposes.

Isoaurostatin, a novel topoisomerase inhibitor produced by Thermomonospora alba.

A novel inhibitor of topoisomerase I designated as isoaurostatin (1) was isolated from the culture filtrate of Thermomonospora alba strain No. 1520. The structure of 1 was determined to be 6,4'-dihydroxyisoaurone on the basis of spectroscopic (NMR and MS) methods. Compound 1 inhibited the relaxation activity of calf thymus topoisomerase I in a noncompetitive manner and did not inhibit the relaxation and decatenation of human placenta topoisomerase II. Compound 1 is an inhibitor belonging to cleavable complex-nonforming type without DNA intercalation.

ChemInform Abstract: Topostatin, a Novel Inhibitor of Topoisomerases I and II Produced by Thermomonospora alba Strain No. 1520. Part 3. Inhibitory Properties.

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Topostatin, a novel inhibitor of topoisomerases I and II produced by Thermomonospora alba strain No. 1520. III. Inhibitory properties.

A novel inhibitor of topoisomerases designated as topostatin was isolated from the culture filtrate of Thermomonospora alba strain No. 1520. The inhibitory activity of topostatin was shown to be pH- and temperature-dependent with a maximum around at pH 6 and 28 degrees C. The stability of topostatin decreased with decreasing pH and rising temperature. Topostatin inhibited topoisomerases I and II in a competitive manner with respect to DNA. The inhibitor also inhibited some restriction endonucleases such as Sca I, Hind III and Pst I, but not Alu I, Bam HI, Eco RI, RNase A, DNase I, DNase II and DNA ligase. Topostatin did not induce the nuclear accumulation of p53 protein by DNA damage in the normal human cells.

Topostatin, a novel inhibitor of Topoisomerases I and II produced by Thermomonospora alba strain No. 1520. II. Physico-chemical properties and structure elucidation.

Topostatin is a new topoisomerase inhibitor isolated from the culture filtrate of Thermononospora alba strain No. 1520. The inhibitor inhibits topoisomerases I and II, and it has neither ability to stabilize the cleavable complex nor ability to intercalate into DNA strands. The molecular formula of topostatin was determined as C36H58N4O11S based on the FAB-MS analyses, and the structure was elucidated to be a novel 14-membered ring containing peptide and terpenoid by various NMR spectroscopies.

Spectral characterization of c-type cytochromes purified from Beggiatoa alba

Three c-type cytochromes were purified from the filamentous sulfur-oxidizing bacterium, Beggiatoa alba strain B18LD, by ammonium sulfate fractionation, flat bed isoelectric focusing and gel filtration. Two of the cytochromes; flavocytochrome c-554 and cytochrome c′, were similar to cytochromes found in anoxygenic photosynthetic bacteria. Flavocytochrome c-554 had an apparent molecular weight of 21,000, an isoelectric focusing point at pH 4.4, contained FMN as the flavin component and had absorption maxima at 410, 450 and 470 nm in the oxidized form and at 417, 523 and 554 nm in the dithionite-reduced from. Cytochrome c′ was also an acidic protein with a pI of 4.8 and an apparent molecular weight of 18,000. The absorption spectra maxima were at 400, 490 and 635 nm in the oxidized form, at 424 and 550 nm in the dithione-reduced form and at 415 and 555 nm in the dithionite-reduced plus CO form. The third cytochrome characterized, cytochrome c-553 had an apparent molecular weight of 13,000, an isoelectric point at pH 4.4 and showed absorption maxima at 411 nm in the oxidized form and at 418, 523 and 553 nm in the dithionite-reduced form. Cytochrome c-553 was also isolated as a complex with a non-heme protein with a molecular weight of 16,000. The non-heme protein altered the absorption spectra and isoelectric point of cytochrome c-553.

Ultrastructure of Beggiatoa alba Strain B15LD

SUMMARY: The ultrastructure of Beggiatoa alba strain B15LD was examined in detail using thin section and freeze-etch techniques. The cell wall complex consisted of five discrete layers external to the cytoplasmic membrane. The surface layer was the most distinct, containing linearly arranged longitudinal fibrils, 10-12 nm in diameter. Sulphur inclusions observed in thin sections had a 12-14 nm thick pentalaminar envelope and were external to the cytoplasmic membrane. Similar pentalaminar envelope structures were observed in cells grown without hydrogen sulphide, but they were small, folded and probably lacked sulphur. After a few hours of exposure to hydrogen sulphide, large sulphur inclusions were present in the cells, presumably due to the expansion of the folded ‘rudimentary’ vesicles to accommodate the deposited sulphur. The location and morphology of the cytoplasmic membrane invaginations which surrounded the sulphur inclusions were elucidated by thin sectioning and freezeetching. A three-dimensional model of the cell envelope structure is presented.

Mixotrophic and heterotrophic growth of Beggiatoa alba in continuous culture.

Beggiatoa alba strain B18LD was grown in continuous culture under heterotrophic conditions on acetate or acetate and asparagine and under mixotrophic conditions on acetate plus either 1 mM sodium sulfide or 1 mM sodium thiosulfate. Considerable differences were observed between the yields and the cell compositions of heterotrophic and mixotrophic cultures at all dilution rates tested. The dry weight yield per gram acetate utilized was approximately three times higher in the acetate-sulfide mixotrophic culture than in the acetate heterotrophic culture, whereas the poly-beta-hydroxybutyric acid and carbohydrate contents were much higher in the heterotrophic cultures. The high yields (0.52--0.75, corrected for the weight of the sulfur) obtained with the mixotrophic cultures imply that the acetate was utilized mainly for biosynthesis. Thus, the oxidation of sulfide supplied energy. The addition of catalase to the chemostat cultures increased yields slightly, but it was insufficient to explain the differences between the heterotrophic and the mixotrophic cultures.

Structure of the sulfur inclusion envelopes from four beggiatoas

The sulfur inclusions from four strain ofBeggiatoa alba were observed by using a ruthenium red-glutaraldehyde technique and a modified Ryter-Kellenberger technique. Three of the four strains contained 4-to 5-nm-thick, single, electron-dense, layered sulfur inclusion envelopes. The fourth strain (B15LD) contained a complex pentalaminar sulfur inclusion envelope, 12–14 nm thick. The sulfur inclusions from all four strains were external to the cytoplasmic membrane but internal to the complexBeggiatoa cell walls. Freeze-etching of theB. alba strain B18LD trichomes revealed the unusual cross-fracture morphology of the sulfur in the inclusions. Fractures around the sulfur inclusions revealed a surface similar to that of the fractured cytoplasmic membrane.